The present invention relates to a new and improved low-pressure or die-casting method and apparatus for the performance thereof.
Generally speaking, the method of die-casting molded parts or castings within a displaceable mold according to the invention and the apparatus for the performance thereof incorporates a pressure tight closed vessel or basin which is provided at its upper side with a casting hole or aperture equipped with a riser or up tube immersing into a part of the molten metal or melt. During the casting process the gas chamber located above the melt is acted upon by a gas pressure which forces the melt into the mold. After the solidification of the cast piece or casting the gas chamber located in the basin or vessel is vented of the gas pressure prevailing therein.
For many years casting molds have been manually fabricated. Accordingly, the molten metal is poured directly out of a melting furnace into a mold by means of a scoop. To prevent the formation of pipes at the casting the mold is carefully manually erected or lifted during the filling process. The forming, cooling and finishing of the mold equally is manually performed. This work requires great dexterity, experience and concentration of the caster and constitutes a considerable safety risk.
Thus, attempts have been made to mechanize or automate the casting process, i.e. the timewise correct erection of the mold during casting is accomplished by a machine, as is likewise the forming, cooling and finishing. The filling of the melt again was manually carried out by means of a scoop which still constituted a source of danger.
The mechanization or automation was further developed by resorting to the use of a rotary or turret table. The mold was erected upon the furnace through a gas-heated coupling system and the molten metal or melt was forced out of the furnace into the mold by compressed or pressurized air. By further turning or indexing the revolving table there were performed, partially automatically and partially manually, at appropriate stations the further working cycles known from manual casting operations.
It has been found that with casting devices of this type there occur leakage problems at the coupling system. With the notoriously well known, especially stringent requirements of a casting plant a rotary table only can be precisely guided for a very limited period of time. As a result, there frequently occur interruptions in the casting operation and serious accidents due to outflowing or pressed-out melt.